Decanting apparatus

ABSTRACT

A decanting apparatus for a wastewater treatment reactor includes a clarified fluid receiver having fluid receiving ports therein, support structure for maintaining the fluid receiver at a desired level within the reactor and flap means selectively biased to occlude the ports of the receiver during mixing cycles so as to prevent entry of sludge into the receiver and to selectively allow entry of clarified fluid through the ports when the sludge is settled. When the valve is closed, the biasing means urges the flap to reseal the ports of the receivers so that sludge does not enter the receiver during sludge mixing cycles within the reactor. The receiver support structure includes an articulated and flexible joint to connect the receiver to the wall of the reactor, yet allow the receiver to maintain a desired level relative to fluid in the reactor and further maintain the receiver at a desired depth beneath the surface of the liquid level within the reactor to prevent floating debris from entering the receiver.

BACKGROUND OF THE INVENTION

The present invention relates to decanter systems and, in particular, todecanter systems for utilization with wastewater treatment reactors.

Certain wastewater treatment processes, especially those utilizingsequential batch reactor techniques or processes, require that clarifiedfluid be periodically withdrawn from the reactor or digester withinwhich the process is occurring. Such decanters must be functionalthroughout the year, even in environments where the lower temperatureextremes may form ice upon the upper layer of the fluid within thereactor. It is also important that the decanting system not entrainsludge during mix cycles within the reactor or have sludge settle withinthe decanting system such that when clarified liquid is withdrawn, acertain amount of sludge is withdrawn with the liquid, as suchentrainment would discharge highly polluted effluent.

One of the major problems with previous decanter systems for use inbatch reactors has been that a receiver for the decanter has had theinterior thereof open to the fluid within the reactor during sludgemixing cycles. When the sludge is being mixed with the incoming effluentand the entire reactor is in a generally mixed state, sludge is near thetop of the reactor as well as the bottom. If the receiver is open atthis time, the sludge usually enters the receiver and settles thereinduring settling cycles.

Thereafter, when the clarified fluid is withdrawn through the receiver,the sludge that is within the receiver is entrained with the clarifiedfluid to pollute the effluent. One solution to this problem is towithdraw the clarified fluid with a pump and have a cycle at thebeginning of the withdrawl of the clarified fluid in which a certainamount of this fluid is directed back to the reactor so as to return theentrained sludge. Such a solution requires a pump and control mechanismor the like and close control of the recycle of the clarified fluid tothe reactor.

Other attempts to resolve the problem of sludge settling within thereceiver, have been directed to physically removing the receiver fromthe tank during mixing cycles. This typically requires a cumbersome andexpensive structure which is suitably strong to hold a decanting systemout of the reactor fluid during the mix cycle. In addition, wherefreezing is likely to occur, fluid within the decanting structure mayfreeze if raised from the liquid in the reactor or, the fluid level atthe top of the reactor may freeze which may make it difficult orimpossible to raise and lower the decanting structure.

Other problems associated with the decanting structure are that thereceiver should be sufficiently spaced from the sludge layer to preventaccidental intake of sludge into the receiver. In addition, the receivershould withdraw clarified fluid in such a manner that the withdrawnfluid does not entrain sludge due to high velocities of the withdrawnfluid coming from near the sludge layer or because the withdrawn fluidis taken from directly above the sludge layer.

Also the support structure for the decanter system must allow forvertical movement of the receiver, as the upper liquid level in thereactor may vary substantially during the different cycles therein.Preferably, the support structure allows the receiver to be supported ata generally fixed height beneath the upper liquid level so as to prevententrainment of floating debris or scum into the receiver and articulatedsufficiently so that the receiver may move freely and smoothly while theupper liquid level is varying.

Certain devices such as one designed by Mandt draw clarified fluid fromnear the bottom of the reactor so a siphon can control flow. This drawsfrom precisely the region of heavy sludge which should be avoided.

Finally, it is noted that certain prior art decanting systems haveincorporated extensive and expensive mechanical devices for manipulatingthe fluid receiver, sometimes into and out of the liquid layer withinthe reactor. The complex mechanical devices required for this operationare subject to failure and do not provide a simple and easy method ofpreventing sludge entry into the receiver. These devices often do notfunction well, if at all, where ice is floating on or forming upon theupper layer of the reactor.

OBJECTS OF THE INVENTION

Therefore, the objects of the present invention are: to provide adecanting apparatus for use in conjunction with a wastewater treatmentfacility which is highly effective in preventing sludge from being drawnfrom the reactor during decanting cycles; to provide a decantingapparatus which is adaptable for use in different climates, especiallythose climates wherein ice may form on top of the liquid level in thereactor; to provide a decanting apparatus which prevents scum and debrisfrom being withdrawn with the clarified effluent from the reactor; toprovide a decanting apparatus which is articulated with respect to thereactor and freely moves vertically to compensate for change in theliquid level within the reactor; to provide a decanting apparatus havinga clarified fluid receiver cooperating with a drain to selectivelydischarge fluid, ports allowing fluid to selectively flow into thereceiver and a flap mechanism for selectively covering the ports duringsludge agitation within the reactor; to provide a decanting apparatushaving a flap mechanism which is normally biased to cover the ports whenthe drain is occluded and which is opened due to the effect of gravityacting on the fluid in the receiver to produce a substantialdifferential pressure across the flap mechanism to allow the flow ofclarified fluid into the receiver when the drain is opened; to provide adecanting apparatus which is relatively inexpensive, easy to operate,and has a relatively long life expectancy.

Other objects and advantages of this invention will become apparent fromthe following description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention.

The drawings constitute a part of this specification and includeexemplary embodiments of the present invention and illustrate variousobjects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic top plan view of a wastewater treatmentfacility showing a pair of wastewater treatment reactors each having adecanting apparatus according to the present invention.

FIG. 2 is an enlarged and partially schematic cross-sectional view ofone of the wastewater treatment reactors, showing the decantingapparatus associated therewith.

FIG. 3 is an enlarged and fragmentary top plan view of the decantingapparatus.

FIG. 4 is a further enlarged and fragmentary view of the decantingapparatus similar to FIG. 3 with portions thereof broken away to showdetail thereof.

FIG. 5 is an enlarged and fragmentary cross-sectional view of thedecanting apparatus, taken along line 5--5 of FIG. 4.

FIG. 6 is an enlarged and fragmentary side elevational view of thedecanting apparatus showing a portion of the clarified liquid receiver,closure flaps associated therewith, and a swivel arm for connection to afloat assembly.

FIG. 7 is an enlarged, cross-sectional view of the clarified liquidreceiver showing a flap assembly in an open position, taken along line7--7 of FIG. 6.

FIG. 8 is an enlarged, fragmentary and cross-sectional view of theclarified liquid receiver showing the flap assembly and similar to theview of FIG. 7 except the flap assembly is in a closed position.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure.

The reference numeral 1 generally designates a wastewater treatmentfacility including a pair of reactors 2 for treatment of wastewater withmicroorganisms and aeration, a reciruclation pump 3 with associatedmanifolds and conduits 4, and a decanting apparatus 5.

Each of the reactors 2 comprises a cylindrical fluid containing tank orreservoir 10 having a side wall 11 and a floor 12. Each reservoir 10holds wastewater fluid 14 being treated therein and the fluid 14 has acyclic level which has a normal high mark generally indicated by thereference numeral 15 and a normal low level mark indicated by thereference numeral 16.

Wastewater to be treated enters through filling means such as themanifold 4 generally at the location with the reference numeral 20 andis distributed along the bottom of the reactors 2 by means oftrident-shaped distribution conduit 22 flow connecting with the manifold4 by downcomer 23 and having a plurality of distribution apertures 25therealong. The distribution conduit 22 also flow connects with thepumps 3 which in turn flow connect with apertures 25 which distributeflow from the pump 3 into a distribution structure 30. The distributionstructure 30 has an internal chamber connecting with a plurality ofdistribution nozzles 31. The nozzles 31 are conical shaped and havedischarge openings 32 therein. Piping and valving of each of the pumps 3may be selectively adjusted so that the pump 3 may draw from thedistribution conduit 22 and discharge through the nozzles 31 or drawthrough the nozzles 31 and discharge through the distribution conduit 22for cleaning of the nozzles 31, as desired. The piping 4 associated witheach pump 3 may also be aligned as sludge removal means to dischargesludge drawn from the conduit 22 to a sludge collection point (notshown), so that sludge may be withdrawn from the reactor 2.

A pressurized air manifold 37 is connected to a compressed air source,such as air compressors 38 and with the distribution structure 30. Inthis manner, compressed air can be selectively mixed with the wastewaterfluid in the distribution structure 30 such that the wastewater exitingthe nozzles 32 is highly oxygenated.

Each decanting apparatus comprises support means, such as supportingstructure 45, a clarified liquid receiver 46, flotation means, such asfloats 47, and a discharge manifold 48. The discharge manifold 48sealably passes through the associated reactor wall 11 and empties intoa municpal sewer, stream or the like (not shown).

The discharge manifold 48 has a control valve 52 positioned therealongvertically spread beneath the normal range of positions for the liquidreceiver 46. The valve 52 may be selectively activated to allow orprevent flow through the manifold 48. The support structure 45 ismedially mounted upon the wall 11 by a flange unit 55. The flange unit55 is connected to a flexible tube 56 which in turn is connected to asupport conduit 57 which also provides structure for the manifold 48passing therethrough. Rigid struts 59 and 60 extend from both the flangeunit 55 and the support conduit 57 respectfully and are pivotally joinedat hinge means such as hinge 61 so that the conduit 57 may be freelyarticulated about the flange unit 55, especially in a vertical plane.

It is foreseen that a suitable manifold 48 between the wall 11 and thereceiver 46 could incorporate flexible tubing along the entire lengththereof and have one or more rigid arms medially articulated extendingbetween the wall 11 and the receiver 46 to provide support for thereceiver 46.

The illustrated receiver 46 is an elongate tube centrally locatedrelative to the conduit 57 and flow communicating internally therewith.The receiver 46 is generally horizontally positioned and remainshorizontally aligned along its axis as the conduit 57 pivots about theflange unit 55 at the hinge 61.

Located at spaced locations along the receiver 46 near the upper sidethereof are a plurality of orifices, openings, apertures or ports 65.The ports 65 open into a central collecting chamber or cavity 66 of thereceiver 46. It is foreseen that other receiver configurations such ascircular or cross-shaped would function as the illustrated elongate tubereceiver 46. Similarly, it is foreseen that a wide variety of shapes ofapertures would function for the purpose of the present invention, forexample, slots.

Flap means, such as flap mechanism 70, are attached to the receiver 46.The flap mechanism 70 includes a relatively inflexible cover plate 72,sealably attached along one side 73 thereof to the receiver 46 andhaving an opposite side 74 which is spaced from the receiver 46. Thecover plate 72 covers, but is spaced from the ports 65. The cover plate72 includes four separate sections 78, 79, 80 and 81 in the illustratedembodiment and opposite ends of each section has an end plate 84 whichseals between the cover plate 72 and the receiver 46.

The flap mechanism 70 also includes a flap 87 attached to the coverplate side 74 by fasteners such as rivets 88. The flap 87 is flexibleand resilient in nature. Preferably, the flap 87 is segmented andgenerally coextensive with the unattached side 74 of each of the coverplate sections 78, 79, 80 and 81. The flap 87 has an attached side 90and an opposite side 91 and is U-shaped or otherwise bent back uponitself such that the flap unattached side 91 is biased or urged againstthe receiver 46 by the resiliency of the flap 87. When the flap 87 ispositioned between the cover plate 72 and the receiver 46, it issomewhat compressed to provide for the biasing effect, but not so muchas to make the flap unattached side 91 unmoveable. A flap 87 constructedof buna-N rubber has proved satisfactory for this purpose. However, abend 94 in the flap 87 is necessarily loose enough to allow the flapside 91 to move away from the receiver 46 when external water pressureis exerted against one side and a partial vacuum against the oppositeside so as to provide a substantial differential pressure gradientacross the flap 87, as the valve 52 opens and drains the receiver 46.When the flap end 91 is against the receiver 46, the flap cover plate 72and end plates 84 cooperate to prevent external water from entering acavity 96 formed thereby and hence from entering the ports 65. It isforeseen that the cavity 96 may provide the function of the ports 65 sothat the aperture blocked by the flap means would be the space betweenthe receiver 46 and the cover plate 72, thereby rendering theillustrated ports unnecessary. The illustrated flap 87 is positioned andconstructed so as to not provide a ledge, lip or other collection pointfor sludge to accumulate during mixing. In particular, the receiver 46slopes downwardly at the location where it is engaged by the flap 87 sosludge is urged to fall to the bottom of the reactor 2 rather thancollect at that location.

It is also foreseen that other types of flaps could be utilized for thepurpose described, that is, to prevent flow of fluid across the openingoccluded by the flap and into the clarified fluid receiver when theclarified fluid discharge is blocked or shut off such that the clarifiedfluid in the receiver becomes stagnant and reaches general equilibriumwith the fluid outside of the receiver. On the other hand, when thedrain on the receiver is open so that the clarified fluid can draintherefrom, a partial vacuum may be produced within the receiver andthere is a differential pressure on opposite sides of the flap createdby fluid pressure exterior of the receiver and this vacuum. At thistime, the flap should open to allow clarified fluid to enter thereceiver. The flap is therefore biased to prevent fluid from enteringthe receiver when draining is not desired and swings open to allowpassage of clarified fluid into the receiver when draining is desired.

Connected to the receiver 46 near opposite ends thereof are the floats47. The illustrated floats 47 are elongate foam filled tubes which areconnected near their center to the receiver 46 by swivel connectors 98.Each of the swivel connectors 98 include.a flange member 99 slidablyencircling the manifold 46, a connecting link 100, and a second flangemember 101 surrounding an associated float 47. The floats 47 are allowedto pivot or swivel freely relative to the receivers 46 upon the swivelconnectors 98 such that the floats 47 may remain relatively horizontallyaligned on the fluid surface. The floats 47 are vertically spaced abovethe receiver 46 by the links 100 and, in this manner, the floats 47remain close to or at the upper fluid level in the reactor 2 whereas thereceiver 46 remains spaced somewhat below the upper fluid level toprevent scum and floating debris from entering the ports 65.

In use, a reactor 2 is typically partially prefilled with fluid to alevel such as noted at 16 from previous usage and this includes asubstantial amount of activated sludge within the fluid 14. Additionalwastewater to be treated is added to the reactor to bring the fluidlevel up to the location noted by the reference numeral 15. Thereafter,the fluid is agitated and/or aerated in accordance with the desiredsequential batch reactor treatment, after which all agitation of theliquid 14 is stopped, so that the sludge therein may settle to thebottom. There then remains a clarified liquid layer 110 at the top ofthe reactor 2 such as between the levels as indicated by the referencenumerals 15 and 16. During agitation, the valve 52 is closed andclarified liquid 11 is allowed to stagnate within the support conduit 57and receiver 46. As the differential pressure between the inside of thereceiver 46 and the exterior thereof is approximately the same when thevalve 52 is closed, the flap 87 closes or seals against the receiver 46,as seen in FIG. 8, so as to operably prevent fluid 110 inside thereactor 2 from entering the collection cavity 66 of the receiver 46.

When it is desired to drain the clarified fluid 110, the valve 52 isopened so that held clarified fluid 11 drains from the conduit 57 andthe receiver 46. This produces a partial vacuum within the receiver 46and a substantial differential pressure across the flap 87 between theinterior and exterior of the receiver 46. The flap unattached end 91then swings about the bend 94 up and away from the receiver 46 such thatclarified fluid may flow beneath the flap 87, as seen in FIG. 7, andthrough the cavity 96, thereafter through the port 65, and thereafterinto the cavity 66 of the receiver 46 for eventual discharge through theconduit 57 and valve 52. The valve 52 remains open until the clarifiedfluid 110 is drained to a desired level, after which the valve 52 isshut. At this time, the flap 87 reseals against the receiver 46 toprevent flow of additional clarified fluid 110 into the receiver cavity66.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown.

What is claimed and desired to be secured by Letters Patent is asfollows:
 1. A decanting apparatus for removing an upper fluid layer froma wastewater treatment reservoir; said apparatus comprising:(a) a fluidreceiver having an interior chamber; (b) support structure means formounting said receiver in the reservoir; said support structure meanscooperating with said receiver for maintaining said receiver at agenerally constant depth relative to an upper fluid level within thereservoir during decanting; (c) an aperture in said receiver forcommunicating between said reciever interior chamber and fluid in thereservoir; (d) means designed for preventing sludge from entering saidinterior chamber when not decanting including:(1) flap means selectivelycovering said receiver aperture; and (2) biasing means cooperating withsaid flap means to selectively cover said aperture when not decantingsuch that said flap means operatively prevents entry of fluid into saidreceiver through said aperture when decanting is not occurring and suchthat said flap means allows flow of fluid into said chamber through saidaperture when decanting is occurring, and for preventing substantialquantities of sludge from accumulating in said receiver when fluid insaid reservoir containing sludge is being agitated between decantingperiods.
 2. An apparatus according to claim 1 including:(a) a draincommunicating with said chamber; and (b) a valve in said drain; saidvalve being positioned below said flap means such that when said valveis open, fluid gravity flows from said chamber such that fluid externalof said chamber exerts a positive pressure on said flap means andthereby opens said flap means so as to allow fluid external of saidchamber to flow into said chamber through said aperture and when saidvalve is closed said flap means is urged by said biasing means to coversaid aperture and prevent external fluid from entering said chamber. 3.The apparatus according to claim 1 wherein said support structurecomprises:(a) an elongate drainage conduit operably flow connected tosaid receiver at one end and adapted for passing through a wall of thereservoir at an opposite end; (b) hinge means on said conduit to allowsaid conduit to swing in a vertical plane; and (c) float means connectedto said receiver and maintaining said receiver at a relatively fixeddepth relative to an upper level of fluid in which the apparatus issubmerged.
 4. The apparatus according to claim 3 in combination with awastewater treatment reservoir.
 5. The apparatus according to claim 1wherein:(a) said float is attached to said receiver by a swivelconnector and is spaced vertically above said receiver so as to maintainsaid receiver at a fixed relative position beneath the surface of aliquid in which said apparatus is located.
 6. The apparatus according toclaim 5 wherein:(a) said flap means includes a cover plate attached nearone end thereof to said receiver and near an opposite end thereof tosaid flap member; (b) said cover plate being spaced from but in coveringrelation to said aperture; and (c) said flap member being generallyU-shaped and being attached along one side thereof to said cover plateand having an opposite side biased to engage said receiver.
 7. Theapparatus according to claim 1 wherein said receiver comprises:(a) anelongate tube having a central cavity and an aperture opening into saidcavity.
 8. The apparatus according to claim 7 wherein said flap meanscomprises:(a) a flexible and resilient flap member positioned such thatthe resiliency of said member normally biases said member toward saidreceiver.
 9. In a decanting apparatus for selectively removing aclarified fluid from a wastewater treatment reservoir wherein the fluidis alternatively agitated with sludge and settled; said apparatusincluding a receiver, a support structure for said receiver and a draincommunicating with a collecting chamber in said receiver; theimprovement wherein:(a) said receiver includes an aperture communicatingbetween said chamber and an exterior thereof; and including (b) a flapcooperatively positioned relative to said aperture to selectively blockflow of fluid through said aperture when said reservoir is beingagitated for substantially preventing sludge from entering said receiverduring agitation of said reservoir and for alternatively allowing flowof fluid through said aperture into said reservoir during decaning. 10.The apparatus according to claim 9 including:(a) biasing means forcontinuously urging said flap to block flow through said aperture insuch a manner that flow may occur if such urging is overcome by apressure differential across said flap.
 11. The apparatus according toclaim 10 wherein:(a) said flap is U-shaped, compressed and resilientsuch that the resiliency of said flap inherently functions as saidbiasing means.
 12. The apparatus according to claim 10 wherein:(a) saiddrain includes a valve; and (b) said biasing means urges said flap toprevent fluid flow into said aperture when said drain valve is closedand said biasing means allows said flap to open to allow flow of fluidthrough said aperture and out said drain when said valve is open. 13.The apparatus according to claim 12, wherein:(a) said valve ispositioned lower than said flap such that when said valve is open, fluidin said drain exits said drain and fluid surrounding said receivercreates a positive pressure on said flap so as to open said flap andallow flow of fluid through said receiver into said drain.
 14. Theapparatus according to claim 13 wherein:(a) said flap means includes acover plate attached near one end thereof to said receiver and near anopposite end thereof to said flap member; (b) said cover plate beingspaced from but in covering relation to said aperture; and (c) said flapmember being generally U-shaped and being attached along one sidethereof to said cover plate and having an opposite side biased towardsaid receiver.
 15. A sewage treatment system comprising:(a) a reservoirsuitable for holding a wastewater fluid for treatment therein; (b)filling means for placing additional wastewater fluid in said reservoir;(c) sludge removal means for removing sludge concentrated from saidwastewater fluid from said reservoir; and (d) a decanting apparatus forremoving clarified fluid from said reservoir; said decanting apparatuscomprising:(1) a fluid receiver having an interior chamber; (2) supportstructure means for mounting said receiver in the reservoir; saidsupport structure means cooperating with said reservoir for maintainingsaid receiver at a generally constant depth relative to an upper fluidlevel within said reservoir during decanting; (3) an aperture in saidreceiver for communicating between said interior chamber and fluid insaid reservoir; (4) flap means selectively preventing flow of fluid fromsaid reservoir into said receiver aperture; and (5) biasing meanscooperating with said flap means to selectively prevent flow of fluidthrough said aperture during agitation of the fluid in said reservoirwith sludge such that said flap means operatively prevents entry ofsubstantial amounts of sludge into said receiver through said aperturewhen decanting is not occuring and such that said flap means allows flowof fluid into said receiver through said aperture after agitation hasstopped and said sludge has settled and when decanting is occurring andfor precluding the collection of substantial quantities of sludge insaid receiver prior to decanting and thereafter withdrawn with decantedfluid.
 16. A sewage treatment system comprising:(a) a reservoir suitablefor holding a wastewater fluid for treatment therein; (b) filling meansfor placing additional wastewater fluid in said reservoir; (c) sludgeremoval means for removing sludge concentrated from said wastewaterfluid from said reservoir; and (d) a decanting apparatus for removingclarified fluid from said reservoir; said decanting apparatuscomprising:(1) a fluid receiver having an interior chamber; (2) supportstructure means for mounting said receiver in the reservoir; saidsupport structure means cooperating with said reservoir for maintainingsaid receiver at a generally constant depth relative to an upper fluidlevel within said reservoir during a decanting cycle; said supportstructure means comprising:(i) an elongate drainage conduit operablyflow connected to said receiver interior chamber at one end and passingthrough a wall of said reservoir at an opposite end; (ii) hinge means onsaid conduit to allow said conduit to swing in a vertical plane relativeto said wall; and (iii) float means connected to said receiver formaintaining said receiver at a relatively fixed depth with respect to anupper level of fluid in which the apparatus is submerged; (3) anaperture in said receiver for communicating between said receiverinterior chamber and fluid in the reservoir; (4) flap means selectivelypreventing flow of fluid from said reservoir into said receiveraperture; said flap means comprising:(i) a flexible and resilient flapmember positioned such that the resiliency of said member normallybiases said member to such a position to prevent flow of fluid throughsaid aperture; (ii) said flap means includes a cover plate attached nearone end thereof to said receiver and near an opposite end thereof tosaid flap member; (iii) said cover plate being spaced from but incovering relation to said aperture; and (iv) said flap member beinggenerally U-shaped and being attached along one side thereof to saidcover plate and having an opposite side biased to engage said receiver;and (5) biasing means cooperating with said flap means to selectivelyprevent flow of fluid into said aperture during agitation of fluid withsludge in said reservoir such that said flap means operatively preventsentry of fluid into said receiver chamber through said aperture whensubstantial quantities of sludge are present throughout said fluid andwhen decanting is not occurring and such that said flap means allowsflow of fluid from an upper portion of said reservoir into said receiverchamber through said aperture when agitation is stopped and sludge issettled to a lower portion of said reservoir and, when decanting isoccurring, for precluding entry of a substantial amount of sludge intosaid receiver.